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EQUINE HEALTH
Veterinarians at the Scone Equine Hospital were strongly encouraging breeders to submit all aborted fetuses and membranes to the laboratory for routine testing (for Herpes virus and other pathogens) and to assess whether Chlamydia is a possible factor in the abortion.
droppings and secretions dry out, dust particles that include the bacteria can get into the air. The most common way someone gets infected is by breathing in dust from these dried secretions. Less commonly, birds infect people through bites/pecks and beak-to-mouth contact.
Psittacosis in humans is generally a mild illness. The most common symptoms include fever and chills, headache, muscle aches and dry cough. Most infected people begin developing symptoms within 5 to 14 days after exposure to the bacteria. In general, people do not spread the bacteria that cause psittacosis to other people, but this is possible in rare cases.
Sporadic outbreaks of psittacosis have occurred in the United States secondary to occupational exposure (usually exposure to birds), with the most recent outbreak being 13 confirmed cases
in Georgia and Virginia in 2018. One study examining the incidence of psittacosis in the United States concluded that during the years of 1999 to 2006, the reported cases of psittacosis varied between 12 and 25 annually, indicating an incidence of 0.01 per 100,000 population. Studies that have examined hospitalized patients with pneumonia have found psittacosis being the cause of pneumonia in less than 5% of cases. According to the CDC, there has been a decline in reported psittacosis cases in humans in the U.S. since 1988.
The disease is more common in Australia. For example, there have been two outbreaks in Australia in towns surrounded by a large population of wild birds. In Australia and New Zealand, it has also been shown to cause abortion in mares.
PSITTACOSIS AS A CAUSE OF ABORTION IN MARES
Due to an increase in sporadic cases in horses in Australia during the past decade, the Scone Equine Hospital in New South Wales (NSW) posted a message about psittacosis on their website in August of 2021 to alert horse owners to be aware of this disease.
Ever since the 2015 breeding season, Scone Equine Hospital and the DPI (Department of Primary Industries) in NSW have been conducting an investigation into the possible
role of Chlamydia psittaci in equine abortion/ stillbirth/neonatal illness seen in that region.
In 2020 there was also a small cluster of cases of Psittacosis in veterinary students who were involved in treating a sick newborn foal at a university veterinary school. This resulted in the DPI testing samples from multiple equine abortions. Chlamydia psittaci bacteria were detected in a small number of those equine abortions in NSW in 2020 and again in 2021. Because this particular bacterium was not tested for prior to 2020, it was uncertain whether Chlamydia was the cause of the abortions or simply an incidental finding.
Veterinarians at the Scone Equine Hospital were strongly encouraging breeders to submit all aborted fetuses and membranes to the laboratory for routine testing (for Herpes virus and other pathogens) and to assess whether Chlamydia is a possible factor in the abortion. The message stated: “As the relevance of these positive Chlamydia results in horses is currently unclear, we do not wish to cause unnecessary concern, however awareness of potential for human illness and the importance of hygiene procedures are obviously important.”
Anyone coming into contact with aborted material was advised to undertake careful hygiene procedures when dealing with equine abortions/stillbirths/neonatal illness cases. “This should include wearing gloves and in particular, P2 masks (for respiratory protection) when dealing with these cases. Routine cleaning and disinfection of themselves and equipment is very important. People who have potentially been exposed are advised to seek medical attention if any of the symptoms apply and to advise their doctor of possible exposure to C. psittaci. The disease can be treated with antibiotics.”
Regarding human exposure and illness, information on Psittacosis was also posted on the Worms & Germs Blog, which is an educational website coordinated by Drs. Scott Weese and Maureen Anderson of the Ontario Veterinary College’s Centre for Public Health and Zoonoses in Canada in 2017. On August
3, 2017, Dr. Weese described the results
from a report of human infection linked to
There was a case where five of the nine people that had contact with the fetal membranes developed psittacosis, and the timing of when they got sick was consistent with exposure at the time of contact.
contact with a mare’s placenta. This report was published in One Health earlier that year.
That paper described five human cases of psittacosis linked to contact with a mare’s placenta. The mare foaled on a breeding farm, where two people were in attendance and a third person examined the fetal membranes after foaling. The placenta appeared to be abnormal and the foal died a week later but was not tested for C. psittaci.
The fetal membranes were taken to the local veterinary school by one of the farm personnel, who was also a vet student, and examined by two staff members and three students. Five
of the nine people who had contact with the fetal membranes developed psittacosis, and the timing of when they got sick was consistent with exposure at the time of contact. Direct contact with these membranes was the only significant possibility for the infections, and no other reasonable sources - such as bird contact, were identified. Two of the five affected individuals were hospitalized, but they all recovered.
Preventing this type of human infection comes down to careful attention to hygiene, especially hand washing, and wearing personal protective equipment or dedicated clothing
to reduce contamination and tracking around of microbes. When attending a foaling, careful handling of the placenta, cleaning and disinfecting equipment and areas that might
Anyone coming into contact with aborted material is advised to undertake careful hygiene procedures including wearing gloves and respiratory protection masks.
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